Combination point former and thread roller machine

ABSTRACT

An in-line, inclined gravity feed track for automatically feeding headed work blanks in sequence through a forging type point forming station having a rotary dial indexing mechanism. The indexing mechanism is selectively adjustable relative to the forging dies, and the entire point forming station is adjustable as a unit relative to the feed track. A thread rolling station is in aligned spaced apart downstream relation to the point forming station and effects work blank rolling movement in a substantially horizontal direction normal to the straight line path of travel of the work blanks in the feed track. A sensing system continuously monitors feeding of blanks in the feed track for deactivating operation of the point forming station.

United States Patent 11 1 Morton 1 Sept. 18, 1973 1 COMBINATION POINT FORMER AND THREAD ROLLER MACHINE [75] Inventor: Robert D. Morton, West Hartford,

Conn.

221 Filed: June3, 1971 21 App1.No.: 149,520

[52] U.S. Cl l0/4, 10/9, 10/21,

10/23, 10/165, 10/169 [51] Int. Cl B2lh 3/06, 823g 9/00 [58] Field of Search 72/88, 90, 89; 10/4,

10/9, 21, 31,155 A, 165, 169, 39, 52, 23, 24; 90/89, 58 A; 29/38 A, 38 B; 408/45, 50, 71,

AIR SUPPLY 3,314,261 4/1967 Grohoski et al. 10/4 X 1,184,033 5/1966 Scofield... 10/4 X 2,832,971 5/1958 Tesch 10/21 3,056,981 10/1962 Byam 10/21 3,398,413 8/1968 Skierski 10/21 X Primary Examiner-Charles W. Lanham Assistant Examiner-E. M. Combs Attorney-Prutzman, Hayes, Kalb & Chilton [57] ABSTRACT An in-line, inclined gravity feed track for automatically feeding headed work blanks in sequence through a forging type point forming station having a rotary dial indexing mechanism. The indexing mechanism is selectively adjustable relative to the forging dies, and the entire point forming station is adjustable as a unit relative to the feed track. A thread rolling station is in aligned spaced apart downstream relation to the point forming station and effects work blank rolling movement in a substantially horizontal direction normal to the straight line path of travel of the work blanks in the feed track. A sensing system continuously monitors feeding of blanks in the feed track for deactivating operation of the point forming station.

LIZ

PAIENIEIJSEPI ems 53,9 0

sum 1 or 3 INVENTOR ROBERT D. MORTON ATTORNEYS PATENTEUSEMW 3.758.900

snimufs FIG. 3

COMBINATION IOINT FORMER AND THREAD ROLLER MACHINE This invention generally concerns machines for making screws and similar articles and particularly concerns a combination machine for performing sequential work blank forming operations in a continous operating cycle of themachine.

A primary object of this invention is to provide an improved combination machine for effecting point forming and thread rolling operations such that work blanks need be handled only once in an operating cycle featuring automatic sequential feeding and forming of the blanks.

Another object of this invention is to provide an improved combination machine of the type described which is quick and easy to set up and adjust for work blanks of different size.

A further object of this invention is to provide such an improved combination machine featuring efficient, high performance point forming forging dies and which is particularly suited to continuously monitor work blank feeding for controlling the operation of the point forming station independently of a downstream thread rolling station.

Still another object of this invention is to provide an improved combination machine of the type described which may be manufactured and assembled at a reduced cost and which occupies a reduced amount of floor space.

A still further object of this invention is to provide such an improved combination machine particularly suited for producing a superior work product and which is capable of economically producing quality specialty fasteners which heretofore have been laborious and costly to make, such as gimlet point screws, pinched point machine fasteners and drill point screws.

Other objects will be in part obvious and in part pointed out in more detail hereinafter.

A better understanding of the objects, advantages, features, properties andv relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth an illustrative embodiment and is indicative of the way in which the principle of the invention is employed.

In the drawings:

FIG. 1 is a partial plan view of the machine of this invention;

FIG.2. is a side elevational view of the machine of FIG. 1; and

FIG. 3 is an enlarged isometric view of part of a point forming station of the machine and which for clarity of illustration is shown in mirror-image relation to its illustrated position in FIG. 1. 7

Referring to the drawings in detail, a preferred embodiment of a combination point former and thread roller machine 10 incorporating this invention is shown having a frame 12 with a hopper 14 mounted thereon for receiving a large quantity of work blanks 16. The frame 12 includes a table surface 18 in inclined relation to the horizontal. The hopper 14 is shown having a typical clearing wheel 20 which is adjustable for ensuring that a head of each blanks is properly positioned in an upper feed chute 22 of an inclined gravity feed track 24 to just pass under the clearing wheel 20.

The feed track 24 includes in addition to the upper chute 22, a lower feed chute 26. As illustrated, the

upper and lower chutes 22, 26 are in-linc and their inclined mounting at approximately 30 to the horizontal in parallel relation to the table 18 ensures that the blanks are first carried by gravity to a point forming station or pointer 28 which is operable to point the blanks and then to a thread rolling station or threader 30 wherein the threads are rolled on the pointed blanks to complete a fastener forming operation.

Adjustment of the slot width and height of the upper and lower chutes 22, 26 in accordance with varyingblank sizes is effected by conventional track spacing adjusting assemblies 32 (shown only on upper chute 22 in FIG. 1 for clarity). Free and easy transfer of blanks from their respective feed chutes to the work stations is facilitated by the provision of track ends 34 and 36.

set by suitable track width adjusting knobs 42 ofa con-.

ventional type. I

For matching operating speed to the rate at which blanks are fed from the hopper l4, conventional variable speed drives (not shown) maybe provided on both pointer 28 and threader 30, and a complete operation is performed each time a main crank shaft 44 for the pointer 28 and a crank wheel 46 for the threader 30 rotate through one revolution. For driving the pointer 28, a motor (not shown) is operably connected, preferably through a suitable variable speed drive (not shown), to power operate a belt drive to a pulley 48. In the specific illustrated embodiment, the pulley 48 is shown connected through a conventional clutch mechanism 50 to rotate the main crank shaft 44 of the pointer 28. A connecting rod 52 provides a driving connection between the main crank shaft 44 and a ball joint 54 pivotally secured to a slide 56.

Rotation of the crank shaft 44 thereby causes the slide 56 to reciprocate within suitable bearing means' 58 supported on the table 18 along an axis of movement contained in a horizontal plane and which extends substantially perpendicular to the path of movement of the blanks in the feed track 24. The slide 56 is suitably secured by removable fasteners (not shown) to a movable die housing 60 suitably mounted for reciprocation on a pair of support posts (one shown at 62 in FIG. 3) received in a fixed die housing 64 secured to a mounting block 66 attached to the machine frame 12.

Upon installing an appropriate set of dies, the movable pointer die 68 is accordingly secured through its housing 60 to the slide 56 for following movement toward and away from the fixed die 70. Both dies 68, 70

time the crank shaft 44 rotates through one complete revolution.

As best seen in FIG. 3, a blank positioning and indexing mechanism 72 is mounted on a generally L-shaped frame member 74 supported on a base 76. The base 76 is supported on the mounting block 66 for swinging movement about a horizontal axis toward and away from the upper chute 22. Such construction permits ready assembly and disassembly of the upper track end 34 (which is desirably mounted on the indexing mechanism 72) and also effects facile installation and removal of the pointer dies 68, 70 relative to their respective die housings 60, 64. More specifically, the base 76 is supported on a pivot shaft 78 fixed to the mounting block 66 and is normally held in place with a suitable releasable locking fastener.

To carry blanks 16 from the track end 34 into position between the pointer dies 68, 70, an indexing dial 80 is rotatably mounted on the bottom of the L-shaped frame member 74, and peripheral notches are shown circumferentially formed about the outer periphery of the dial 80 for receiving blanks in sequence from the track end 34.

The blanks 16 are indexed a quarter turn clockwise as shown in FIG. 1 into position between the dies 68, 70. Indexing dial movement is effected by a ratchet 82 operated by an advance pawl 84, the ratchet 82 being supported on the top of the frame member 74 in coaxial driving relation to the dial 80. Pawl 84 is driven by an index plunger 86 supported in the frame member 74. The plunger 86 will be understood to be spring returned for actuation by an operating lever 88 carried by the movable die housing 60.

To accommodate blanks having shanks of different lenght, the dial 80 and its frame member 74 are adjustable in height on the base 76 relative to the dies 68, 70. For this purpose the frame member 74 is formed with a dovetailed portion 90 received within a corresponding channel 92 in the base 76, and a suitable lead screw 94 and adjusting handle 96 (FIG. 2) is supported on the base 76 and threadably engaged with the frame member 74 for positioning the height of the dial 80 relative to the dies 68, 70.

By virtue of the above arrangement, the pointer 28 in its entirety may be supported on an extension portion 98 of the frame 18 located behind the threader 30 such that the entire point forming station may be selectively raised and lowered as a unit relative to the height of the threader 30 and the feed track 24. For this purpose, a lead screw mounting device 100 is operatively secured to the frame extension portion 98 for supporting a lead screw 102 having an adjustment handle 104 at one end. The lead screw 102 is shown threadably connected to the mounting block 66 of the point forming station for raising and lowering the entire point forming station as a unit (including its illustrated drive components) relative to a pre-established height of the upper and lower chutes 22, 26.

Accordingly, the dial 80 may not only be selectively adjusted by its blank length adjustment device relative to the pointer dies 68, 70 in accordance with a predetermined shank length, but the entire point forming station may be raised or lowered in relation to the feed track 24 to ensure smooth, trouble free blank feeding without disturbing the positioning of either the upper or lower chutes 22, 26.

From the pointer 28, a column of pointed blanks are then fed in the same sequence to the threader 30 upon each blank 16 carried by the dial 80 being indexed an additional quarter turn clockwise (FIG. 1) from a posi' tion between the dies 68, 70 into registry with the lower inclined gravity feed chute 26. Each blank is fed between the thread rolling faces of a fixed thread rolling die 108 and a movable die 110 having a reciprocating drive of a type well known in the art.

As fully described in US. Pat. No. 3,308,642, issued Mar. 14, 1967, entitled Thread Rolling Machine" and assigned to the assignee of this invention, a main slide 112 carrying the movable die 110 is reciprocated relative to the fixed dies 108 by a pitman 114 pivotally secured at its opposite ends to the main slide 112 and the crank wheel 46 which is suitably rotated by a motor through a conventional drive mechanism (not shown). The fixed die 108 is detachably mounted to a stationary die block 116 by an adjustable clamp 118 and the movable die 110 is mounted to the slide 112 by adjustable clamps 120. The slide 112 is mounted for reciprocable movement on a slide block 122 which will be understood to be adjustable for setting the alignment and spacing of the fixed and movable thread rolling dies 108, 110.

As described in the referenced patent, a combination gate and starting finger 124 is mounted at the discharge opening of the track end 36 for oscillatory movement generally parallel to and between dies 108, 110. Finger 124 is driven for successively feeding a blank from the track end 36 into position between leading edges of the dies 108, 110 in timed relation to reciprocable movement of the slide 112, thereby to both gate the chute 26 as well as to wedge each pointed blank in succession between the dies 108, 110. 5

The gate and starting finger 124 is driven by an annular cam 126 concentrically mounted on a wheel 46 as described in the referenced patent, and a crank 128 is drivingly connected to the cam 126 to effect oscillatory movement of the finger 124. To accommodate adjustable positioning of the finger 124 in a plane parallel to the working faces of the thread rolling dies 108, 110 and perpendicular to the table 18, the finger 124 is adjustably mounted by a clamping device 130 on a control arm 132 pivotally mounted on the table 18 at 134 and operatively connected to the crank 128 by an adjustable variable length connecting rod 134.

The above-described construction provides several notable advantages. A significant feature is that blanks need only be handled once. No special blank transfer apparatus or complex handling means is required. The machine is of simplified construction and inherently occupies less floor space. Blanks can be made with exactly the right amount of metal for rolling a gimlet point, e.g., since the relative position of the pointer dies 68, 70 and head of the blank is easily adjusted. The resulting fasteners are of a quality superior to blanks which are unpointed prior to being rolled and which so frequently result in the ends or points being strung out and weakened. In addition, the described machine is particularly suited for producing drill point (or selfdrilling screws) as well as screws having a pinched point with or without machine screw threads extending down onto its pointed tip. Both drill point and pinched point screws must be pointed before being rolled, and the machine of this invention is particularly suited to economically produce such fasteners.

Yet another feature of the c0mbination machine 10 resides in a significantly simplified drive control system for monitoring its operation and interrupting the output of the pointer 28 upon a change in normal loading of the blanks in the feed track. This feature is particularly important, e.g., to prevent excessive blank loading of the lower feed chute 26 leading to the threader. in addition, in the production of drill-point screws, the required forging-type pointing dies are relatively complex and are normally set such that they would damage one another if operated without a blank being positioned between the dies.

To ensure that pointer 28 will not operate in the absence of a continuousflow of blanks to the pointer 28 from the upper chute 22, the loading of the blanks in the feed chute 22 upstream of the pointer 28 is monitored by any suitable means, such as photoelectric devices or fluid operated devices. In the specific illustrated embodiment, the upper chute 22 will be understood to be provided with suitable openings (such as at 136 in FIG. 2) in opposed alignment on opposite sides of the chute 22 in spaced upstream relation to pointer 28. Suitable tubing 138 is shown for connecting one of the track openings to a source of compressed air 140 through an adjustable air pressure regulator 142. The opposed track opening may likewise be connected by tubing, e.g., to a diaphragm operated, normally open switch of a sensor or detector 144.

In the absence of blanks interrupting the air flow, the detector 144 will sense an unrestricted steady state flow of compressed air across the upper chute 22 and under such conditions will be pneumatically operated to indicate a change in normal blank loading of the chute 22 due to the absence of blanks being fed to the pointer 28. Steady state air flow will immediately overcome the spring loading on the diaphragm 147 to close the, switch of detector 144 and complete a suitable electric circuit 146 to a conventional solenoid operated normally open valve 148 communicating through air passage 150 to the air supply 140.

Upon being energized by the electrical signalproduced by operation of the detector 144, the valve 148 closes to shut-off and vent compressed air in lines 152, 154 respectively leading to conventional clutch and brake mechanisms 50 and 156. The clutch and brake mechanisms 50, 156 each have return spring loaded, fluid operated pistons 158, 160 within housings 162, 164 shown mounted adjacent opposite ends of the main crank shaft 44 of the pointer 28.

Relief of the air pressure within the housings 162, 164 automatically permits springs 166, 168 to operate to respectively engage the brake 156 and disengage the clutch 50 relative to the crank shaft 44, thereby positively deactivating the drive to the pointer 28. Thereafter, upon again filling the upper chute 22 with blanks and with the air detector device and valve conditioned for operation, the pistons 158, 160 may be operated under the force of the supply air pressure to overcome their respective springs 166, 168 to release the brake 156 and re-engage the clutch 50 to again efi'ect operation of the drive mechanism to the point forming station.

A similar sensor or detector device 144A is provided in the lower chute 26 between the pointer 28 and the threader 30 to sense the presence of pointed blanks adjacent the point forming station. However, in this arrangement the detector 144A operates when a column of blanks interrupts an unrestricted steady state flow of air through tubing 138A and releases a spring loaded diaphragm 147A to close a normally open switch in the detector 144A to provide a signal to the solenoid valve 148 indicative of a change in normal blank loading of the chute 26. The signal to the valve 148 again automatically deactivates the pointer drivemechanism in the same manner as described above to stop the flow of blanks through the pointer 28 and prevents the lower chute 26 from becoming excessively filled with pointed blanks and thereby effectively minimize any possibility of'the lower chute becoming jammed and possibly damaging any components of the point forming station.

The described pointer drive control system is of particular significance in an automatic high production sequential work forming operation of the type for which the combination machine 10 is particularly suited, especially in view of the amplified forces imparted by the operating components. Accordingly, undesired effects from any deviation from normal blank loading and feeding in the feed chutes 22, 26 caused, e.g., by unintended jamming of the chutes, inadvertent stoppage of the threader 30 or any other abnormal feeding condition is effectively minimized. The sensors or detectors 144, 144A are intentionally located relative to the pointer 28 and their chutes 22, 26 such that operation of the pointer is terminated well before chute 22 is emptied and/or chute 26 becomes filled.

A machine constructed in accordance with this invention is particularly suited to provide specialized fasteners and is also significantly more economical not only to manufacture and assemble but also to operate. Reduced costs are associated with the combination assemblies supported on a common frame in a compact arrangement, and also with the savings realized in a reduction in the floor space required as compared to two separate machines. The simplified blank loading sensing and drive control systemfeatured in this machine effectively minimizes any possibility ofjamming of the work blanks and other resulting damage to machine parts, while ensuring a continuously smooth, automatic, high production operation. Since the blanks are continuously produced in sequence, undesired mixing and potentially costly mismatch of the dies and blank sizes is minimized. Ready adjustment and quick and easy machine set up is provided for forming fasteners of different shank length. No need exists for handling the blanks more than once, and this advantage is a particular benefit with respect to pointed fasteners for once the points have been formed, the blanks must be very carefully handled to Avoid nicking.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

1 claim:

1. A combination machine for making threaded articles from work blanks in automatic sequential operations comprising a point forming station including a forging type reciprocable die means and a rotary dial indexing mechanism which is adjustable relative to the reciprocable die means, a machine frame, a power operated thread rolling station operatively supported on the machine frame, a feed track on the machine frame including a feed chute adjustable in height relative to the machine frame for supplying blanks to the point forming station and an additional feed chute adjustable in height relative to the machine frame for receiving pointed blanks from the point forming station and delivering the pointed blanks to the thread rolling station, movable mounting means mounted on the machine frame and supporting the point forming station as a unit on the machine frame, a height adjustment device interconnecting the mounting means and the machine frame for selectively moving the point forming station in its entirety to adjust its height relative to the machine frame and the feed track, a power operated drive for operating the point forming station for pointing each blank by a single forging blow, and a drive control system for controlling the drive for the point forming station, the drive control system including a sensor for monitoring the feed track, the sensor being operable in response to a change in normal loading of the blanks in the feed track and causing the drive control means to deactivate the drive for the point forming station.

2. The combination machine of claim 1 wherein the sensor monitors the first feed chute to detect an absence of blanks therein being supplied to the point forming station, wherein the drive control means operates to deactivate the drive for the point forming station prior to the blanks being emptied from said first feed chute, wherein the sensor monitors said additional feed chute to detect the presence of pointed blanks therein adjacent the point forming station, and wherein the drive control means operates to deactivate the drive for the point forming station prior to said additional feed chute becoming fully loaded with pointed blanks.

3. The combination machine of claim 1 wherein the drive for the point forming station includes a disengagable fluid operated clutch providing a driving connection to the point forming station, and a fluid circuit including passage means for supplying fluid under pressure and control means for controlling fluid pressure in the passage means, the passage means being connected between the control means and the fluid operated clutch, the control means being activated in response to a signal from the sensor for causing a change in fluid pressure in the passage means for diengaging the fluid operated clutch to interrupt the drive for the point forming station.

4. The combination machine of claim 1 wherein the thread rolling station is power operable in timed relation to the drive for the point forming station with the output of the point forming and thread rolling stations being at substantially the same cyclic rater 5. A machine comprising a point forming station, a thread rolling station, a feed track including a feed chute for supplying blanks to the point forming station and an additional feed chute for receiving pointed blanks from the point forming station and delivering the pointed blanks to the thread rolling station, the point forming station including pointing die means and a blank positioning and indexing mechanism operative in timed relation to operation of the die means for feeding blanks from the feed track to the die means and discharging pointed blanks therefrom, the blank positioning and indexing mechanism being selectively adjustable in height relative to the die means, and the point forming station in its entirety being selectively adjustable in height as a unit relative to the feed track for accommodating blanks of varying shank length.

6. The machine of claim 5 further including a frame for the machine supporting the feed track in fixed relation thereto, a mounting block mounted on the frame for supporting the point forming station, a base member secured to the mounting block and supporting the die means in fixed relation thereto, and a frame member for the blank positioning and indexing mechanism supported on the base member, the blank positioning and indexing mechanism being adjustable in position on its frame member for selective height adjustment relative to the die means, and the mounting block being adjustable in position on the machine frame for selective height adjustment of the point forming station as a unit relative to the machine frame and feed track.

7. The machine of claim 5 wherein the pointing die means includes power operated reciprocable forgingtype die means operable at a preselected cyclic rate, and wherein the thread rolling station is power operated in timed relation to the operation of the reciprocable forgingtype die means of the point forming station such that the output from each station is substantially the same.

8. The machine of claim 6 wherein the base member is pivotally supported on the mounting block for swinging movement toward and away from the feed track.

9. The machine of claim 6 wherein first and second lead screws are mounted respectively on the machine frame and base member, and wherein the first and second lead screws are threadably engaged with the mounting block and frame member for selectively adjusting the height of the point forming station and blank positioning and indexing mechanism respectively. 

1. A combination machine for making threaded articles from work blanks in automatic sequential operations comprising a point forming station including a forging type reciprocable die means and a rotary dial indexing mechanism which is adjustable relative to the reciprocable die means, a machine frame, a power operated thread rolling station operatively supported on the machine frame, a feed track on the machine frame including a feed chute adjustable in height relative to the machine frame for supplying blanks to the point forming station and an additional feed chute adjustable in height relative to the machine frame for receiving pointed blanks from the point forming station and delivering the pointed blanks to the thread rolling station, movable mounting means mounted on the machine frame and supporting the point forming station as a unit on the machine frame, a height adjustment device interconnecting the mounting means and the machine frame for selectively moving the point forming station in its entirety to adjust its height relative to the machine frame and the feed track, a power operated drive for operating the point forming station for pointing each blank by a single forging blow, and a drive control system for controlling the drive for the point forming station, the drive control system including a sensor for monitoring the feed track, the sensor being operable in response to a change in normal loading of the blanks in the feed track and causing the drive control means to deactivate the drive for the point forming station.
 2. The combination machine of claim 1 wherein the sensor monitors the first feed chute to detect an absence of blanks therein being supplied to the point forming station, wherein the drive control means operates to deactivate the drive for the point forming station prior to the blanks being emptied from said first feed chute, wherein the sensor monitors said additional feed chute to detect the presence of pointed blanks therein adjacent the point forming station, and wherein the drive control means operates to deactivate the drive for the point forming station prior to said additional feed chute becoming fully loaded with pointed blanks.
 3. The combination machine of claim 1 wherein the drive for the point forming station includes a disengagable fluid operated clutch providing a driving connection to the point forming station, and a fluid circuit including passage means for supplying fluid under pressure and control means for controlling fluid pressure in the passage means, the passage means being connected between the coNtrol means and the fluid operated clutch, the control means being activated in response to a signal from the sensor for causing a change in fluid pressure in the passage means for diengaging the fluid operated clutch to interrupt the drive for the point forming station.
 4. The combination machine of claim 1 wherein the thread rolling station is power operable in timed relation to the drive for the point forming station with the output of the point forming and thread rolling stations being at substantially the same cyclic rate.
 5. A machine comprising a point forming station, a thread rolling station, a feed track including a feed chute for supplying blanks to the point forming station and an additional feed chute for receiving pointed blanks from the point forming station and delivering the pointed blanks to the thread rolling station, the point forming station including pointing die means and a blank positioning and indexing mechanism operative in timed relation to operation of the die means for feeding blanks from the feed track to the die means and discharging pointed blanks therefrom, the blank positioning and indexing mechanism being selectively adjustable in height relative to the die means, and the point forming station in its entirety being selectively adjustable in height as a unit relative to the feed track for accommodating blanks of varying shank length.
 6. The machine of claim 5 further including a frame for the machine supporting the feed track in fixed relation thereto, a mounting block mounted on the frame for supporting the point forming station, a base member secured to the mounting block and supporting the die means in fixed relation thereto, and a frame member for the blank positioning and indexing mechanism supported on the base member, the blank positioning and indexing mechanism being adjustable in position on its frame member for selective height adjustment relative to the die means, and the mounting block being adjustable in position on the machine frame for selective height adjustment of the point forming station as a unit relative to the machine frame and feed track.
 7. The machine of claim 5 wherein the pointing die means includes power operated reciprocable forging-type die means operable at a preselected cyclic rate, and wherein the thread rolling station is power operated in timed relation to the operation of the reciprocable forging-type die means of the point forming station such that the output from each station is substantially the same.
 8. The machine of claim 6 wherein the base member is pivotally supported on the mounting block for swinging movement toward and away from the feed track.
 9. The machine of claim 6 wherein first and second lead screws are mounted respectively on the machine frame and base member, and wherein the first and second lead screws are threadably engaged with the mounting block and frame member for selectively adjusting the height of the point forming station and blank positioning and indexing mechanism respectively. 